The 3.8 percent tax is aimed at the unearned income of wealthier taxpayers, but since it is not indexed for inflation middle-income taxpayers will eventually pay the tax.
Lawmakers in 1969 created a similar situation when it passed the Alternative Minimum Tax and did not properly index it for inflation.
Congress now tweaks the tax annually (known as a "patch") to ensure it doesn't affect most middle-class taxpayers. The cost for the patch increases every year to keep pace with inflation. Last year's patch was roughly $70 billion.
During the health care debate on Thursday, Senate Finance Chairman Max Baucus (D-Mont.) acknowledged that lawmakers were creating another AMT situation with the Medicare tax, but still urged passage of the bill.
"We don't want to get another AMT situation... We're now paying the price today," he said, adding, "But this is not the time and place."